488 Scientific Proceedings, Royal Dublin Society. 



bably a red ochre." Substances now known as ochres consist of 

 highly ferruginous clays. 



Sandaracha. SavSa^oa/crj or Sav§ajoax»? (St. Mark MS.)- This 

 was realgar, the red arsenic disulphide, Asg S2. Both this sub- 

 stance and ochre were found in the island of Topazos in the Eed 

 Sea. 



Telloivs. 



All pigments of this colour examined by Davy proved to be 

 iron ochres, sometimes mixed with a little red lead. " Orpiment 

 was undoubtedly employed, as is obvious from what Pliny said on 

 the subject." Davy found in one instance massicot, or lead pro- 

 toxide, mixed with some red lead. 



Misy. Miav (St. Mark MS.) was a yellow copperas. 



Greens. 



ChrysocoUa. XpvcroKoXXa (Leyden MS.). This was a green- 

 coloured paint, and, from Pliny's description of it, could have been 

 nothing else but the basic carbonate of copper, now known as 

 malachite. All green paints examined by Davy were carbonates 

 of copper. The mineral chrysocolla is a blue silicate of copper, 

 CuSi03-2H.O. 



Artificial Colouiis. 



Meds. 



Cerussa usta and minium both signify red lead; this is an 

 artificial colour made by roasting lead. 



" Sandyx was made by torrefying equal parts of true sandar- 

 acha and sinopis," that is to say, by heating a mixture of realgar 

 and ochre. 



Siricum. ^ipiKov (St. Mark MS.). This was made by mixing 

 sinopis with sandyx. 



Blues. 



The blue pigment Kvavov (St. Mark MS.) is made by preparing 

 a frit or glass made from wood ashes, or alkali, sand, and copper ore. 

 It is very largely employed in the different apartments of the Baths 

 of Titus. Different shades of colour were obtained by an admixture 

 of body colour, most usually chalk. This pigment is quite un- 

 altered by exposure to the air and suu. 



